JP3234038B2 - Heat exchanger for semiconductor processing liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger for a semiconductor processing solution, and more particularly, to the structure of a heat exchange section of a thermostatic apparatus used for controlling the temperature of a corrosive chemical or the like.

[0002]

2. Description of the Related Art Heat exchangers used for semiconductor processing liquids are:
The processing liquid is brought into contact with the heat exchange substrate, and the processing liquid is cooled or heated through the heat exchange substrate.

When a highly corrosive chemical such as a semiconductor processing solution is used, not only does the reaction rate change drastically depending on the temperature of the solution, but it is also used to form a fine element. Therefore, it is necessary to always pay close attention to the control of the liquid temperature, and it is necessary to use a material having a high resistance to the semiconductor processing liquid as the heat exchange substrate material.

Conventionally, as a heat exchanger for such a semiconductor processing liquid, a stainless steel plate coated with a fluorine resin coating on a processing liquid contact surface has been used. However, the coating has fine holes. In addition, since the resin itself has the property of allowing gas to permeate therethrough, though slightly, the treatment liquid and the gas permeate through the coating, resulting in the following various inconveniences.

[0005] That is, the processing solution and the gas that have reached the stainless steel react with the stainless steel to generate a new gas, and the gas generated by the reaction pushes up the fluororesin film to form a space. This space reduces the efficiency of heat exchange, and furthermore, the coating is cracked by gas pressure, which causes the treatment liquid to come into direct contact with the stainless steel, and a large amount of metal ions generated by the reaction between the treatment liquid and the stainless steel. There is a problem that it is mixed in the processing solution.

Therefore, the present inventor has proposed a heat exchanger for a semiconductor processing solution in which at least the semiconductor processing solution contact surface side of the heat exchange substrate is made of high-purity silicon carbide ceramics (Japanese Utility Model Publication No. 1-332362). ).

This silicon carbide ceramic has excellent resistance to chemicals such as a semiconductor processing solution, and even if it reacts slightly, since silicon carbide is a component of silicon and carbon, they are harmful to the semiconductor. It does not become a serious ion.

[0008] However, since a binder is used in forming the ceramics, it is inevitable that some components of the binder are slightly contained as impurities. For this reason, there has been a problem in that this elutes into the semiconductor processing solution during long-term use.

Furthermore, there has been proposed a heat exchanger in which at least a treatment liquid contact surface side of a heat exchange section is covered with a silicon carbide film formed by a CVD method (chemical vapor deposition method), that is, a CVD silicon carbide film. (Japanese Patent Application No. 3-33128).

According to this structure, there is an advantage that it is not necessary to use the substrate material limited to silicon carbide ceramic and the workability is facilitated. Further, the CVD silicon carbide film does not use a binder, and has high purity and extremely high resistance. In particular, CVD silicon carbide films
The content of harmful alkali metal and heavy metal impurities in the semiconductor processing liquid can be 5 ppm or less.

[0011]

However, if a CVD silicon carbide film without pinholes is to be formed, the film thickness must be increased, and it takes time to form the film. In addition, in order to shorten the formation time, a method such as raising the substrate temperature is adopted, and the surface of the film becomes rough,
There is a problem that the film quality is deteriorated. The roughness of the film surface is a serious problem, for example, since the air-tight sealing is performed using an O-ring, and if the film is rough, the air-tightness is reduced and liquid leakage occurs. Therefore, conventionally, a method of forming a CVD silicon carbide film and then performing mirror finishing has been adopted, which causes a cost increase and has a problem that surface contamination cannot be avoided.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat exchanger for a semiconductor processing solution which is inexpensive, contains no harmful impurity components, and has high reliability.

[0013]

Therefore, according to the present invention, a silicon carbide (SiC) ceramic is used as a heat exchange substrate, and at least the treatment liquid contact surface side is made of a silicon carbide film formed by a PVD method, preferably a sputtering method. Coated.

[0014]

According to the above structure, the silicon carbide film may be formed only on the necessary surface of the silicon carbide heat exchange substrate processed into a desired shape, and the film does not necessarily have pinholes completely. Because we do n’t need to be empty,
The film thickness may be as thin as, for example, about 5 μm. Therefore, film formation can be performed in a short time. In addition, since a dense and thin film can be formed, the surface roughness after the film formation is almost the same as the surface roughness of the silicon carbide substrate before the film formation, and the mirror surface state can be maintained. Therefore, unlike the case of using the conventional CVD silicon carbide film, the polishing process for improving the surface roughness, which is performed after the film formation, is not necessary. This is effective in preventing the surface cleanness from being lowered.

As the PVD method, in addition to the sputtering method, a vacuum evaporation method such as an electron beam evaporation method is used.

In particular, the sputtering method may be performed using silicon as a target in an atmosphere containing carbon, or using silicon carbide as a target. In particular, CVD silicon carbide has an alkali metal / heavy metal impurity content of 5 ppm which is harmful in semiconductor processing solutions.
The following can be achieved, and the purity is extremely high. By using this as a target, an extremely reliable silicon carbide sputtering film can be formed.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The heat exchanger according to the embodiment of the present invention is shown in FIGS.
As shown in FIG. 5, the heat exchange substrates 1 and 2 are made of a silicon carbide ceramic substrate, and are characterized in that their surfaces are coated with a sputtered silicon carbide film in order to prevent a reaction with a semiconductor processing chemical.

That is, this heat exchanger is composed of a silicon carbide ceramic substrate 20 and heat exchange substrates 1 and 2 whose surfaces are covered with a sputtered silicon carbide film 21 having a thickness of 5 μm. The heat exchange chamber 4 is formed to be opposed to the heat exchange chamber 4, and the heat exchange chamber is configured to control the temperature of, for example, a semiconductor processing chemical solution led out of the processing container by a pipe or the like.

Further, this apparatus is configured to be cooled or heated by the thermo modules 5 and 6, respectively, and the heat radiating sides of the thermo modules 5 and 6 are cooled by cooling water introduced through cooling pipes 7 and 8, respectively. The heat radiation blocks 9 and 10 to be cooled are brought into contact with each other. Then, when the semiconductor processing chemical is introduced into the heat exchange chamber via the first pipe 11, the liquid is cooled in the heat exchange chamber 4 and then returned to the processing vessel via the second pipe 12. Further, the periphery of the heat exchanging section is hermetically sealed by an O-ring O whose surface in contact with liquid is made of fluorine resin.

In forming the sputtered silicon carbide film, a silicon carbide film formed by a CVD method is used as a target to a thickness of about 5 μm.

In this apparatus, the temperature of the semiconductor processing chemical can be favorably controlled over a long period of time without the heat exchange substrate coming into contact with the processing chemical and mixing impurities.

Further, since the sputtered silicon carbide film is simply formed thinly on the surface of the silicon carbide ceramic, and it is sufficient to form the film only on the liquid contact surface, the cost is significantly reduced.

Furthermore, since the surface roughness is very small and close to a mirror surface, the O-ring O is used to seal the airtightness so as to be extremely good, and there is no liquid leakage. In the above embodiment, a sputtered silicon carbide film was formed using silicon carbide formed by the CVD method as a target.
A target formed by a method other than the method may be used. Alternatively, silicon may be used as a target and the target may be formed in a carbon atmosphere. In the above-described embodiment, the film is formed by the sputtering method. However, the film may be formed by another PVD method, for example, a vacuum evaporation method.

Also, the side wall may be formed of a silicon carbide block having a silicon carbide film formed on the surface, and the shape may be appropriately changed.

In addition, in the above embodiment, a thermo module is used as a means for cooling or heating the processing liquid. However, other cooling and heating means may be used instead of the thermo module. Needless to say.

[0027]

As described above, according to the heat exchanger for semiconductor processing liquid of the present invention, the heat exchange substrate is made of silicon carbide ceramic, and the processing liquid side is covered with a PVD silicon carbide film. Therefore, it is possible to obtain a highly reliable heat exchanger that does not contain harmful impurities in the semiconductor processing liquid at extremely low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a heat exchanger for semiconductor processing liquid according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the heat exchange substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat exchange board 2 Heat exchange board 3 Side wall body 4 Heat exchange chamber 5 Thermo module 6 Thermo module 7 Cooling pipe 8 Cooling pipe 9 Heat radiating block 10 Heat radiating block 11 First pipe 12 Second pipe O O ring 20 Carbonization Silicon ceramic 21 Sputtered silicon carbide film

Continuation of the front page (56) References JP-A-59-164682 (JP, A) JP-A-2-26823 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21 / 304 648 F28F 19/02 501

Claims (2)

(57) [Claims] 1. A heat exchanger for cooling or heating a semiconductor processing liquid by bringing the processing liquid into contact with a heat exchange substrate, wherein the heat exchange substrate is made of silicon carbide (SiC) ceramic and at least a processing liquid contact surface side is a PVD method. A heat exchanger for a semiconductor processing solution, wherein the heat exchanger is coated with a silicon carbide film formed by the method described above. 2. A heat exchanger for cooling or heating a semiconductor processing solution by bringing the semiconductor processing solution into contact with a heat exchange substrate, wherein the heat exchange substrate is made of silicon carbide (SiC) ceramic and at least a processing solution contact surface is formed by a sputtering method. A heat exchanger for a semiconductor processing solution, which is covered with the formed silicon carbide film.